And we begin out west, on the front lines, where the sandbags are in place. The barricades are up. And everyone is hoping they are ready for the wind and water pouring in tonight. An evacuation order is in place for 1,000 homes. Families already leaving in fear of floods and the mud. ABC's David Wright, now, starts us off in southern California. Reporter: When it rains, it pours. And that's the problem here in drought-stricken California. Already, these storms have whipped up waves, snapped trees, and caused plenty of wrecks on the roads. More than 100 crashes in L.A. County alone this morning, including this big rig. And the worst may be yet to come. Here in Glendora, they're bracing for mudslides. Last month, these hills were on fire. We were here. This is only the beginning. Reporter: The fire killed off the plants that glue the Earth to the hillsides. So, you bring on the rain -- and you could see a tsunami of thick, rocky mud. Landslides can travel at speeds up to 35 miles per hour. In 1969, a mudslide wiped out 160 homes here in Glendora. It's scary stuff. It is because you never know. Your home can be gone. This home might not be here. If you see pictures from 1969, all the homes up here, you can see is facia and the roof. That was it. Reporter: What can they do to protect themselves? Not much. But throughout these neighborhoods, they are installing concrete barricades, like these. Think of it as a giant funnel, designed to channel the mud all the way down the street. The hope is, it'll leave all those houses intact. The barricades will be here for three to five years, until the vegetation grows back. It's not a lot of curb appeal. But if it's going to keep us safe, I'm all for that. Reporter: From here, the storm heads to the frozen midwest, where blowing snow is wreaking havoc on the roads. And see that steam? It's so cold in Minnesota, lake superior is 50 degrees warmer than the air. Here in Glendora, the forecasters say the second wave of the storm, with the heaviest rains, could hit as soon as tonight. But for now, it's blue skies, Diane. All right, David. Let's bring in meteorologist, ginger zee. She is also in California and watching this storm that will March across the nation. Ginger? Reporter: I assure you, clear skies for not long at all, Diane. The clouds are already thickening. And the deepest and heaviest rain is going to fall, starting early tomorrow morning. We're going to be right there. And I want to show you what the Numbers look like. It's not great because it will come so fast, so quickly. So, it's four to six inches of rain in the area just north and west of Los Angeles. Even that little green spot closer to Santa Barbara, maybe. At seven inches, that's what that represents. Let's do timing. That's what's important. On Friday, the storm starts rocketing through southern California. You get the heavy rains. You get the gusts up to 60-mile-per-hour, 70-mile-per-hour, possibly of waterspouts and weak tornadoes coming onshore. And the storm hits the rockies and the sold air. It will make ice. Freezing rain, sleet, that wintry mix. South of Chicago, through Indianapolis, parts of Ohio and western Pennsylvania, through the weekend. Here it comes again on the weekend. Thank you so much, ginger,

This transcript has been automatically generated and may not be 100% accurate.

Now Playing: Tense Moments for Passengers on American Airlines and Spirit Airlines Flights

Now Playing: {{itm.title}}

{"id":22709383,"title":"Bracing for the Heavy Rains in California","duration":"3:00","description":"Sandbags are in place and thousands have an evacuation order as the region prepares.","url":"/WNT/video/bracing-heavy-rains-california-22709383","section":"WNT","mediaType":"Default"}